A popular purchase from the usual stockists of imported electronic modules is a digital panel meter. A very small amount of money secures a module with a seven-segment display that you can stick on the front of your power supply or project for an easy readout. Even before the advent of these ultra-cheap Chinese products there have been readily available digital meters, in a line stretching back to the 1970s with chips such as the Intersil 7106.
[Marcus Taciuc] is eschewing the off-the-shelf parts, and creating his own digital panel meter. He’s using an MSP430 microprocessor as the brain of his device, and a Hitachi HD44780 compatible LCD display at the front end. The appropriate combinations of resistors and op-amps feeding the MSP’s ADC inputs allow his meter to be used to measure up to 40 VDV, and up to 10A.
He’s put up a video which we’ve included below the break, showing the use to which this meter has been put: replacing the moving-coil meter in what looks like a classic piece of Heathkit equipment. A 3D printed bracket allows the new meter to fit the circular hole of the original meter, with the LCD on the front. You might still order a prefab meter module, but you can’t deny this looks good.
Not all LCD panel meter builds are so polished. A few years ago we brought you one using a dollar store pedometer.